In silver halide color photographic materials, phenol type and naphthol type couplers are well known as cyan couplers in general use.
In recent years, research efforts have been directed to developing novel cyan couplers in which color developability (which relates to the coupling activity and the spectral absorption coefficient of the dye obtained), fastness of the dye image obtained and the absorption properties of the dye image are improved in comparison to phenol type and naphthol type cyan couplers, and high color developability, dye image fastness, and excellent color reproducibility can be provided. Couplers developed through such efforts include, for example, the 3-hydroxypyridine compounds described in European Patent Publication 333,185, the 3H-2-dicyano-methylidenethiazoles described in European Patent Publication 362,808, the 3-dicyanomethylidene- 2,3-dihydrobenzothiophene-1,1-dioxides described in JP-A-64-32260 (the term "JP-A" as used herein means an unexamined Japanese patent application), the pyrazoloazoles described in JP-A-63-264753 and U.S. Pat. No. 4,873,183, the imidazoles described in U.S. Pat. Nos. 4,818,672 and 4,921,783, and JP-A-3-48243, the pyrazolopyrimidones and pyrazoloquinazolones described in European Patent Publications 304,001, 329,036 and 374,871 and JP-A-2-85851, and the condensed triazoles described in European Patent Publication 342,637.
However, the present state of the art is such that the performances of these proposed novel cyan couplers can not simultaneously satisfy the above requirements for excellent color developability, dye image fastness and color reproducibility, and they can not be put to practical use without further research and development.
Further, it has been found that the use of combinations of these couplers, either with or without the above phenol type and naphthol type cyan couplers, tends to degrade the respective couplers' properties rather than to provide an additive or synergystic effect.
Couplers having the same basic structure as the pyrrolotriazole cyan couplers according to the present invention are shown by Formulas (IX), (XIII), (XV) and (XX) of Formulas (II) to (XXXV) in JP-A-62-27855, and two specific examples of couplers within the scope of each of Formulas (IX), (XIII), (XV), and (XX) are shown. Also, in Formulas (I) and (II) of JP-A-62-279340, the same basic structure is shown and 42 specific examples of the compounds are given.
However, the compounds described in JP-A-62-278552 and JP-A-62-279340 are magenta couplers and are different from the cyan couplers of the present invention, which have the same basic structure as that of the above compounds but provide a cyan dye by a coupling reaction with an oxidation product of a color developing agent according to a substituent introduced therein.
Further, in JP-A-1-288855, the compounds represented by Formulas (IV) to (XVII) are disclosed as cyan couplers with a novel basic structure. Of them, the compounds represented by Formulas (IV) and (V) are described as pyrrolotriazole type cyan couplers. In particular, while the compounds represented by Formula (IV) are pyrrolotriazole type cyan couplers with the same basic structure as the couplers of the present invention, the structure shown in the above publication has a different active site from that of the couplers of the present invention, at which the coupling reaction with an oxidation product of a color developing agent occurs. The coupling activity of the couplers exemplified in the above publication is low and it is difficult to put them to practical use.
As described above, the single or combined use of the above novel cyan couplers including the hydroxypyrimidine type cyan couplers as well as the conventional phenol type and naphthol type cyan couplers can not provide performance adequate to simultaneously satisfy all of the requirements for color developability, dye image storing performance, fastness and color reproducibility. The combined use thereof rather reduces and deteriorates the respective excellent performances thereof.
Accordingly, it would be desirable to provide a combination of novel cyan couplers which improves upon the defects of the respective couplers and gives better performance even if used in combination with conventional cyan couplers while maintaining the excellent performances held by the respective couplers.